HBV G145R突变对S蛋白及“a”决定簇合成肽抗原性影响

人工合成G145R突变后HBsAg"a"决定簇多肽G145R-SP24,将G145R-SP24、重组G145R变异S蛋白及重组野生型HBsAg分组免疫BALB/c小鼠,制备相应抗血清。通过观察各免疫原与抗血清或抗G145R变异HBsAg McAb的免疫反应特征,分析并比较G145R突变后对S蛋白及"a"决定簇合成肽抗原性的影响。结果,几种免疫原均取得理想的免疫效果,ELISA证实各抗血清均有较好的特异性。G145R-SP24和G145R变异S蛋白免疫小鼠获得的抗血清效价较野生型HBsAg略低,且抗原性也发生了明显改变,G145R突变后"a"决定簇仍然具有较好的免疫原性;另外G145R-SP24与G145R变异S蛋白之间也显示出不同的抗原性,提示孤立的G145R变异HBsAg"a"决定簇与完整G145R S蛋白的"a"决定簇可能形成不同的空间构象。本研究为进一步探讨"a"决定簇突变后空间结构的变化规律与抗原性改变的特点奠定一定的基础。

Effect of HBV G145R mutation on the antigenicity of S protein and the synthetic peptide of "a" determinant

To investigate the effect of HBV G145R mutation on the antigenicity of S protein and the synthetic peptide of "a" determinant,the recombinant G145R mutant and wide-type HBsAg were used as antigen to immunize BALB/c mice in order to develop the corresponding polyclonal antisera and the immuno-reactivity of immunogen with the polyclonal antisera or the monoclonal antibody of the G145R mutant HBsAg(G145R-McAb)was observed.It was demonstrated that all the immunogens used to immunize BALB/c mice showed excellent immunogenicity and good specificity for the antisera could be demonstrated by ELISA assay.The titer of antiserum against G145R-SP24 and G145R mutant S protein was somewhat lower than that of anti-serum against wide-type HBsAg.Meanwhile,the antigenicity of the G145R mutant S protein and synthetic peptide was obviously changed in comparison with that of the wide-type HBsAg,however,the "a" determinant of G145R mutant HBsAg still remained good immunogenicity.Furthermore,different immunologic characteristics existed between the G145R mutant S protein and synthetic peptide of its "a"determinant,suggesting that the "a"determinant of G145R mutant HBsAg and the synthetic peptide form different steric conformation.These results will provide some foundation for the further studies on the rules of changes on the steric conformation of the mutant HBsAg "a"determinant and the characteristics of antigenicity alterations.